(a) Technical Field
The present disclosure relates to an air blower, and more particularly, to an air blower for a fuel cell vehicle in which a bypass flow ensures a surge margin is used for cooling a motor in order to improve the overall performance of the motor.
(b) Background Art
Generally, a fuel cell vehicle is driven by using electric energy continuously produced by an electric-chemical reaction performed by a reverse reaction of electrolysis of water wherein typically hydrogen from a fuel supplier and oxygen among air from an air supplier are provided to a humidifier. Here, the fuel cell vehicle may include: a fuel cell stack for producing electricity; a humidifier for humidifying and supplying fuel and air to the fuel cell stack; a fuel supplier for supplying hydrogen to the humidifier; an air supplier for supplying air containing oxygen to the humidifier; and a cooling module or device for cooling the fuel cell stack. More specifically, the air supplier may include an air cleaner for filtrating foreign substance contained in the air, an air blower for compressing and supplying the air filtrated in the air cleaner and a control box for controlling the air blower. In such a configuration, one of the most important factors in designing the air blower is that a safe driving region is to be maintained and efficiency increased while at the same time the flow amount and pressure performance meets the necessary requirements of the system.
In an impeller of a general centrifugal compressor provided in the air blower, a surge phenomenon occurs in a low flow amount/high pressure region and as a result the driving region is reduced. When a compressor is driven in the surge region, bearing and other related component, etc., may be damaged as well as serious vibration and noise may be produced.
Since the surge phenomenon occurs in a low flow amount region of a compressor, according to a related art, a high pressure may be obtained in a small flow amount region by throwing exhausting air at an outlet of the compressor. Further, air at an outlet of a compressor is allowed to be re-circulated toward an inlet to thereby reduce flow amount loss and ensure surge margin. In this system, heat is to be produced in a stator and rotor of a motor for driving a compressor due to electro-magnetic loss. This heat produced at the stator can be reduced using an outer case that is air-cooled or alternatively it may be water-cooled. However, the heat produced at the rotor, that is disposed inside the compressor, is difficult to be cooled.
The description provided above as a related art of the present invention is just for helping understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.